@article {IOPORT.05991869,
    author       = {Lohmayer, Robert and Osterloh, Andreas and Siewert, Jens and Uhlmann, Armin},
    title        = {Entangled three-qubit states without concurrence and three-tangle.},
    year         = {2006},
    journal      = {Physical Review Letters},
    volume       = {97},
    number       = {26},
    issn         = {0031-9007},
    pages        = {Article ID 260502, 4 p.},
    publisher    = {American Physical Society, College Park, MD},
    doi          = {10.1103/PhysRevLett.97.260502},
    abstract     = {Summary: We provide a complete analysis of mixed three-qubit states composed of a Greenberger-Horne-Zeilinger state and a $W$ state orthogonal to the former. We present optimal decompositions and convex roofs for the three-tangle. Further, we provide an analytical method to decide whether or not an arbitrary rank-2 state of three qubits has vanishing three-tangle. These results highlight intriguing differences compared to the properties of two-qubit mixed states, and may serve as a quantitative reference for future studies of entanglement in multipartite mixed states. By studying the Coffman-Kundu-Wootters inequality we find that, while the amounts of inequivalent entanglement types strictly add up for pure states, this `monogamy' can be lifted for mixed states by virtue of vanishing tangle measures.},
    identifier   = {05991869},
}